After strong opposition from anti-abortion groups, the Trump administration decided to kill a study that was seeking to use fetal tissue to develop a cure for HIV, and has put the future of all research in doubt.

As the Washington Post noted, the study was using fetal tissue implanted into mice, but that method of research has come under fire from anti-abortion groups. As a researcher at the National Institutes of Health in Montana said in an email obtained by the newspaper, they were directed to stop “procuring fetal tissue” from the only available firm, which brings a halt to their research.

“This effectively stops all of our research to discover a cure for HIV,” the researcher wrote in an email this September.

Though the action was taken in September, it had remained quiet to the public, as government officials forbid researchers to discuss the cuts. As the Washington Post noted, researchers are “incensed” by the decision and the apparent capitulation to the anti-abortion lobby.

“This is scientific censorship of the worst kind,” said Warner Greene, the longtime director of the Gladstone Institute of Virology and Immunology.

Greene told Science Magazine that the decision stunned researchers, and has dealt a significant blow to the collaboration that had taken place in trying to find a cure for HIV.

“We were all poised to go and then the bombshell was dropped,” he said. “The decision completely knocked our collaboration off the rails. We were devastated.”

After the initial story about the cutback was published by Science Magazine, the NIH released a statement saying that it had put a pause in place for procuring new human fetal tissue, but that it was not meant to put an end to existing research. The project in question could still go on, the agency said.

“Research with tissue already on hand could proceed, and NIH leaders asked to be notified by intramural investigators if new procurement would be necessary,” the agency said in a statement. “NIH leadership was not informed that new procurement was necessary for the study you reference in your story. We are looking into why this did not occur.”

But the decision has left an uncertain future for HIV research and left researchers unsure of what would happen with future projects. Even if the administration were to reverse its decision and allow fetal tissue research, the lost time would be significant and some research may have already been lost, Greene said.